Support larger integer test arguments: C part

Change the type of signed integer arguments from int32_t to intmax_t.
This allows the C code to work with test function arguments with a range
larger than int32_t. A subsequent commit will change the .datax generator
to support larger types.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/test_generate_test_code.py b/tests/scripts/test_generate_test_code.py
index 889b962..7c0ac0c 100755
--- a/tests/scripts/test_generate_test_code.py
+++ b/tests/scripts/test_generate_test_code.py
@@ -487,8 +487,8 @@
         self.assertEqual(local, '')
         self.assertEqual(arg_dispatch,
                          ['(char *) params[0]',
-                          '((mbedtls_test_argument_t*)params[1])->s32',
-                          '((mbedtls_test_argument_t*)params[2])->s32'])
+                          '((mbedtls_test_argument_t*)params[1])->sint',
+                          '((mbedtls_test_argument_t*)params[2])->sint'])
 
     def test_hex_params(self):
         """
@@ -503,7 +503,7 @@
                          '((mbedtls_test_argument_t*)params[2])->len};\n')
         self.assertEqual(arg_dispatch, ['(char *) params[0]',
                                         '&data1',
-                                        '((mbedtls_test_argument_t*)params[3])->s32'])
+                                        '((mbedtls_test_argument_t*)params[3])->sint'])
 
     def test_unsupported_arg(self):
         """